Sains Malaysiana 41(11)(2012): 1451–1459

Determination of Herbicide Diuron Levels in Palm Oil Matrices using HPLC-UV

(Penentuan Aras Herbisid Diuron dalam Matriks Minyak Sawit Menggunakan HPLC-UV)

Mohd Izwarie Ramli, Tan Yew Ai & Halimah Muhamad*

Analytical and Quality Development Unit, Malaysian Palm Oil Board, No. 6,

Persiaran Institusi, Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia

Mohd Izwarie Ramli, Zuriati Zakaria

School of Chemical Sciences and Food Technology, Faculty Science and Technology

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

School of Enviromental and Natural Resource Sciences

Faculty Science and Technology, Universiti Kebangsaan Malaysia

43600 Bangi, Selangor, Malaysia

Diserahkan: 19 Disember 2011 / Diterima: 28 Jun 2012

ABSTRACT

The objective of this study was to develop a method for the determination of diuron (3-(3,4-dichlorophenyl)-1,1-dimethyl urea) residue in crude palm oil (CPO) and crude palm kernel oil (CPKO) matrices. The method involves the extraction of the herbicide from the oil matrix using low temperature precipitation and solid phase extraction techniques, detected by high performance liquid chromatography-ultra violet (HPLC-UV). The HPLC separation was carried out on an AscentisTM RP-Amide column and elution with acetonitrile (solvent A) and water-methanol (2:1, v/v) (solvent B) as a suitable solvent system, at ratio of 4:6 (v/v). The optimum volume of acetonitrile for the extraction of diuron was 30 mL and 4 mL was obtained as the optimum volume of the solvent for elution analyte through the SPE cartridge. A linear correlation was obtained for the concentration of diuron from 0.05–1.0 μg mL-1 with a correlation coefficient of 0.99. The recovery of diuron from CPO was 83.2–101.4% with a relative standard deviation of 1.4–9.9% and 79.4–87.9% with relative standard deviation of 0.9–5.6% for CPKO. The method detection limit and limit of quantification obtained were 0.018 μg g-1 and 0.058 μg g-1, respectively. The method was used to determine diuron residues in palm oil from different refineries situated at different locations throughout Malaysia.

Keywords: Crude palm kernel oil; crude palm oil; diuron; herbicide

ABSTRAK

Objektif kajian ini adalah untuk membangunkan satu kaedah bagi menentukan residu diuron (3-(3,4-diklorofenil)-1,1-dimetil urea) di dalam matriks minyak sawit mentah (CPO) dan minyak isirong sawit (CPKO). Kaedah yang dibangunkan melibatkan pengekstrakan herbisid daripada matriks minyak sawit menggunakan teknik pemendakan bersuhu rendah dan pengekstrakan fasa pepejal yang dikesan dengan kromatografi tekanan prestasi tinggi-ultra lembayung (HPLC-UV). Pemisahan dengan HPLC-UV dibuat menggunakan turus AscentisTM RP-Amide dan dielusi dengan asetonitril (pelarut A) dan air-metanol (2:1, v/v) (pelarut B) sebagai sistem pelarut yang sesuai, pada nisbah 4:6 (v/v). Isi padu pelarut asetonitril optimum untuk mengekstrak diuron adalah 30 mL dan 4 mL diperoleh sebagai isi padu pelarut optimum untuk mengelut analit melalui kartrij SPE. Kolerasi lurus diperoleh pada julat kepekatan diuron 0.05–1.0 μg mL-1 dengan kolerasi koefisen 0.9983. Peratus perolehan semula diuron bagi CPO ialah 83.2–101.4% dengan sisihan piawai relatif 1.4–9.9% dan 79.4–87.9% dengan sisihan piawai relatif 0.9–5.6% bagi CPKO. Had pengesanan kaedah dan had kuantitatif yang diperoleh masing-masing adalah 0.018 μg g-1 dan 0.058 μg g-1. Kaedah yang dibangunkan digunakan untuk menentukan residu diuron di dalam minyak sawit daripada kilang penapisan yang berbeza di seluruh Malaysia.

Kata kunci: Diuron; herbisid; minyak isirong sawit; minyak sawit mentah

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*Pengarang surat-menyurat; email: halimah@mpob.gov.my